Words related to brain

bird-brain (n.)
also birdbrain, 1936, slang, "stupid person," also perhaps suggestive of flightiness, from bird (n.1) + brain (n.). Bird-brained is attested from 1910 and bird-witted from c. 1600.
brain trust (n.)
"group of experts assembled to give advice on some matter," occasionally used since early 1900s, it became current in 1933, in reference to the intellectuals gathered by U.S. President Franklin D. Roosevelt as advisers; from brain (n.) + trust (n.).
brain-child (n.)
"idea, creation of one's own mind," 1850, from brain (n.) + child. Earlier was the alliterative brain-brat (1630).
brain-coral (n.)
1709, from brain (n.) + coral; so called for its appearance.
brain-dead (adj.)
"suffering complete loss of brain functioning," 1971 (brain death is from 1968), from brain (n.) + dead. Popularized in U.S. 1975 by journalistic coverage of the Karen Anne Quinlan case.
brain-drain (n.)
"emigration of experts and trained people to richer countries from poorer ones," 1963, from brain (n.) + drain (n.).
brainiac (n.)
"very smart person," 1982, U.S. slang, from brain (n.) + ending from ENIAC, etc. Brainiac also was the name of a comic book villain in the Superman series and a do-it-yourself computer building kit, both from the late 1950s, and the word may bear traces of either or both of these.
brainless (adj.)
late 15c., "witless, stupid," from brain (n.) + -less. Related: Brainlessly; brainlessness.
brain-stem (n.)
1875, from German; see brain (n.) + stem (n.).
brainstorm (n.)

also brain-storm, by 1861 as a colloquial term for "fit of acute delirious mania; sudden dethronement of reason and will under stress of strong emotion, usually accompanied by manifestations of violence," from brain (n.) + figurative use of storm (n.).

The sense of "brilliant idea, mental excitement, fit of mental application," is by 1934 and seems to have evolved from the earlier sense:

Modern radio broadcasting is replete with examples of the resourcefulness, daring and hair-trigger thinking of the men who handle the big news breaks and special programs for the networks — the "brainstorm boys" the announcers and engineers call them. Eye-witness accounts of federal agents surrounding a gang lair, word pictures of dust storms, stratosphere flights, floods and fires — these are but a few of the programs brought to radio audiences by the brainstorm squad. [Popular Mechanics, July 1936]

The verbal meaning "make a concerted attack on a problem, involving spontaneous ideas," is by 1947. Related: Brainstormed; brainstorming.